Mainframe Developer

Job Title:Senior Mainframe COBOL / Natural Developer

Position Overview

Work on enhancing a mission-critical mainframe accounting platform by developing new pooled-account functionality within an established z/OS environment. This role involves extending existing Enterprise COBOL and Natural applications, implementing financial accounting functionality, and ensuring accurate transaction processing, reconciliation, and reporting.

The position requires a developer who can navigate complex legacy applications, trace undocumented logic, and deliver reliable enhancements without disrupting existing production operations.

What You'll Do / Key Responsibilities

• Analyze existing account master, posting, and balance-maintenance programs to identify where new account functionality must be incorporated and document findings.

• Design and develop new account functionality, including master file and table structures, account opening and closing, participant linkage, sweep and reverse-sweep logic, allocation, interest apportionment, and closing balance derivation.

• Modify batch COBOL programs and JCL and extend nightly and month-end processing cycles while maintaining agreed batch-window limits.

• Enhance audit trails, exception reporting, and reconciliation controls in coordination with accounting stakeholders.

• Develop test data, unit and regression test packs, and parallel-run comparisons against current production output.

• Investigate and explain differences identified during testing.

• Support implementation, conversion of in-scope existing accounts, and early-life production runs, including on-call support during initial cycles.

• Prepare program documentation, data-flow notes, and runbook updates for ongoing production support.

Required Qualifications

• 5+ years of Enterprise COBOL development experience in a z/OS environment.

• 5+ years of experience with NaturalOne.

• 3+ years of JCL development and production support experience.

• 3+ years of experience with financial/accounting systems development or support, including double-entry posting, balance/accrual maintenance, value dating, reconciliation, and month-end closeouts in a regulated environment.

• 3+ years of experience working with Adabas and VSAM.

• 3+ years of experience tracing undocumented logic through copybooks, call chains, and job streams.

Preferred Qualifications

• Experience with cash management, account pooling, sweeps, or treasury applications.

• Experience with CA-7 scheduling and batch operations.

• Experience with REXX, Python, or Java.

Additional Skills

• Experience with mixed-estate integration, including calling between COBOL and Natural and exposing mainframe functionality through z/OS Connect, IBM MQ, or REST services.

• Experience with CA-7 batch-window analysis and performance tuning.

• Experience with REXX or CLIST for tooling, and Java or Python for data comparison and migration activities.

• Knowledge of notional and physical pooling, cash concentration, sweeps, and intercompany allocation.

• Ability to take specifications from analysis through production implementation with limited supervision.

• Strong written communication skills, including the ability to explain technical changes to auditors, business analysts, and developers.

• Degree in computer science or a related field, or equivalent practical experience.